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Tropical crop research prompts air pollutant warning

11/03/2009 20:22:58

An “environmentally friendly” tropical crop could lead to hazardous increases in levels of the air pollutant ozone according to new research, led by Lancaster University (UK) and published in the US journal Proceedings of the National Academy of Sciences today (Monday 5th October).

Global production of palm oil now exceeds 35 million tonnes a year, with the average UK supermarket stocking hundreds of products containing it, from processed food like margarine and cakes to cosmetics.

Palm oil is also used for biofuel since it is considered to be more “environmentally friendly” than fossil fuels.

But an international team of scientists on a £2m joint UK/Malaysian research project led by Lancaster University and funded by the Natural Environment Research Council (NERC) have discovered a downside to the increasing global demand for the crop.

A square kilometre of oil palm trees on a plantation emits five times as many volatile organic compounds (VOCs) - a major contributing factor to ozone -as the same area of rain forest. Palm oil plantations also emit more oxides of nitrogen than forests, from fertilised soil as well as from factories and vehicles on the plantations. Unless carefully managed, these nitrogen emissions will increase in the future with increased fossil fuel use.

Project leader Professor Nick Hewitt of the Lancaster Environment Centre at Lancaster University says: “These compounds lead to the production of ground-level ozone, an air pollutant that damages human health, plants and materials, reduces crop productivity and has effects on the Earth’s climate. Although ozone levels are acceptable at the moment, they will increase if oxides of nitrogen are not controlled in the future”.

Study co-author Dr Rob MacKenzie of Lancaster University adds: “When assessing the sustainability of the crop, the effects of plantations on air quality should be considered. Our study provides an early warning of the urgent need to develop policies that manage nitrogen emissions, at the plantation, regional and national scales, if the detrimental effects of palm oil production on air quality and climate are to be avoided.”

The study warns that large scale palm production has the potential for very serious effects on air quality in Asia, as output rises with economic development but Professor Hewitt said it is not too late to act.

”The global demand for oil palm is shooting up and this is an early warning of an unfortunate and inadvertent consequence of producing this crop. The options are to manage the oxides of nitrogen emission by carefully controlling regional industrialisation and the use of fertiliser and fossil fuels in the plantations. The other option is to prevent oil palm trees producing VOCs through genetic modification.”

The study was conducted by the Universities of Lancaster, Leeds, Leicester, East Anglia, Manchester, York, Cambridge, Edinburgh, the University of l’Aquila in Italy, and NERC’s Centre for Ecology and Hydrology and National Centre for Atmospheric Sciences. It was funded by the Natural Environment Research Council (NERC) and it was based in Danum Valley, one of the largest and most important protected areas of pristine lowland rainforests in Southeast Asia. Danum Valley is home to the joint Malaysia - UK Sekhar Foundation & Royal Society's South East Asian Rainforest Research Programme (SEARRP).